Method and apparatus for forming on a substrate a pattern of a material

ABSTRACT

A method for forming on a substrate (108; 214) a pattern of a material, the method comprising: providing (S100) a material layer (104); providing (S104, S106) an adhesive layer (106), wherein at least one of the material layer (104) or the adhesive layer (106) comprises a pattern corresponding to the pattern to be formed on the substrate (108; 214); and transferring (S108) the material to the substrate (108; 214) with the adhesive fixing the material to a surface (110; 216) of the substrate (108; 214). This solves the problem of forming on a substrate a pattern of a material that, in general, cannot be applied to the substrate directly due to the fact that the material cannot be printed and/or has no or reduced adherence properties with respect to the substrate.

BACKGROUND

For providing a pattern or an image of a material, for example aconductive material, on a substrate to form, for example, conductortraces, the material may be treated in such a way that it can be printedonto the substrate directly and after printing shows sufficientadherence properties with regard to the substrate so that the pattern isfixed to the substrate.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an LEP (Liquid Electro Photography)print engine;

FIG. 2 is a flow diagram describing an example of a method for formingon a substrate a pattern of a material;

FIG. 3 shows various examples for transferring a material with a desiredpattern to a substrate when applying a method as described in FIG. 2;

FIG. 4 is a schematic representation of an example of an apparatus forforming on a substrate a pattern of a desired material;

FIG. 5 is a schematic representation of an example of an LEP (LiquidElectro Photography) apparatus for forming on a substrate a pattern of aspecific material;

FIG. 6 is another example of an apparatus for forming on a substrate apattern of a desired material;

FIG. 7 is a schematic representation of an example of an LEP printengine of FIG. 1 which has been modified for printing any type ofmaterial;

FIG. 8 shows an example of a multi-layer structure made by the printingengine shown in FIG. 7;

FIG. 9 shows an example of a multi-layer functional device made by theprinting engine described with respect to FIG. 7; and

FIG. 10 shows a sample of carbon nanotubes printed on paper using the“gluing” concept.

DETAILED DESCRIPTION

For a variety of substrates it may be desired to apply to a surfacethereof a material having a predefined pattern. For example, in thefield of electronics it may be desired to provide a conductor pattern ofan electric circuit on a substrate. In the field of printing, forexample brochures, it may be desired to apply to a portion of thebrochure or to pages thereof a material for obtaining a desireddecorative effect. Other products may be also desired to be providedwith a patterned material to obtain a decorative effect, for examplegreeting cards or the like may be provided with metallic materials toprovide for a glittering effect when light is incident.

For providing patterns on a substrate analog and digital approaches maybe used, such as inkjet printing, LEP (Liquid Electro Photography)printing, and dry EP (Electro Photographic) printing. These techniquesallow precisely forming the desired pattern on the substrate by“printing” the material. The material needs to be “printable” by therespective technique, and has a sufficient adherence property withregard to the substrate to which it is to be applied so that it remainsfixed on the substrate after the printing process.

Unfortunately, not all of the materials which are desired to be providedin a specific pattern on a substrate show such properties. A materialmay be not printable and/or may not show a sufficient adherence propertywith regard to the substrate to which it is to be applied. Thus, even ina case where the material could be printed, it may not sufficientlyadhere to the substrate after being printed. Some materials that can beprinted may be modified, for example by including a polymer to create anadhesive film during printing, to have sufficient adherence property,this may not be possible or desired for all materials as the originalmaterial, on the basis of which the pattern is to be formed, needs to bemodified. This, in addition to the additional labor needed for modifyingthe material, may also effect the appearance and/or a property of thematerial after being applied to the substrate which may not be identicalto the original appearance/property, for example in terms ofconductivity, or in terms of the decorative effect to be achieved.

In other words, printing processes are limited by the range of materialsthey can print. As an example, when inkjet printing materials with largeor heavy particles, for example flakes, these particles tend to sink inthe ink. When LEP (Liquid Electro-Photography) and DEP (Dry ElectroPhotography) printing high-conductance materials, these conductiveparticles in the LEP or Dry-EP presses will short the gap between theelectrodes, and will discharge, thereby preventing their ability formaterial transfer. Moreover, printing of a new material by a printingprocess may require high investment for the development of new ink. Inaddition, the printed material may be typically mixed with a carriermaterial, which might affect its functionality or require apost-printing process to remove.

In the following an approach will be described for forming on asubstrate a pattern of a material that, in general, cannot be applied tothe substrate directly due to the fact that the material cannot beprinted and/or has no or reduced adherence properties with respect tothe substrate. An example of such material, on the basis of which testshave been carried out, are carbon nanotubes which, in an LEP process,can be charged to adhere to the photo imaging plate and to the blanket.However, they will not adhere to a substrate, like paper. For suchmaterials, the subsequently described approach allows the transfer of apattern of such a material to the substrate despite the fact that itcannot be printed and/or has no or reduced adherence properties. Thematerial is provided with an adhesive layer, for example a transparentLEP ink, and the pattern with adhesive ink applied thereto istransferred to the substrate so that the material is fixed to thesubstrate by means of the adhesive material. Also materials which arenot desired to be conditioned or modified can be applied to thesubstrate, e.g. a material which does not provide for the possibility ofbeing combined with polymer materials or other materials for introducingan adherence property in the material.

When considering the field of LEP printing, the LEP process allowsreliably transferring a variety of materials to a substrate at a goodquality. However, there are materials which may create a backgroundimage on the respective drums of the LEP apparatus and/or on the printedsubstrate. Other materials may not be dielectric enough for beingtransferred electrically by the electric field to the photo imagingplate of the LEP apparatus, thereby resulting in a poor quality of theprinted image. Other materials may not be reliably transferred onto thesubstrate due to their low adherence property to the substrate.

The just mentioned materials, by means of the subsequently discussedapproach, can also be applied in a desired pattern onto a substrate.

In an example a wide range of materials may be printed by LEP-basedpresses by making use of the LEP ink, which becomes a sticky polymerlayer (“glue”) when heated. The required material in a dispersed form isapplied, and sticks to the patterned “glue” layer. This capabilityenables LEP-based presses to print many types of materials includingdecorative materials such as decorative flakes, ceramic materials,pharmaceuticals, and functional materials as conductors andsemi-conductors.

FIG. 1 is a schematic diagram of an LEP (Liquid Electro Photography)print engine, e.g. an HP Indigo print engine. The LEP process isdescribed with respect to the print engine of FIG. 1. A photoconductor10 (PIP—photo imaging plate) is charged by a charge roller 12. A laserwriting head 14 (WH—writing head) discharges the required image patternonto the PIP 10 (forming of a latent image), followed by an electricaltransfer of charged LEP ink from one of the Binary Ink Development (BID)units 16 a-16 g onto the discharged regions of the PIP 10. The ink isthen transferred to the blanket (ITM—intermediate) drum 18 where itundergoes drying and softening-melting using both internal and externalheaters 20. The dry-melted ink emerges from the ITM drum 18 as a tackyfilm similar to “hot melt glue” and finally the ink is pressed onto amedia received between the ITM drum and the impression (IMP) drum 22 andadheres to it.

The resin in the ink allows printing on almost any substrate. Thisproperty of the ink (printable on almost any substrate) allows makingmost materials adhere to the resin. This character of LEP ink to behaveas glue may be exploited for printing “non-printable” materials. Theability to print “non-printable” materials may increase theattractiveness of any printing system, and the applications may rangefrom attractive graphics enhancement features (e.g. glitteringmaterials) to functional printing (e.g. printed electronics). Thepossibility of low-cost layering of functional materials as variablestructures allows creating inexpensive devices for low-cost applicationssuch as RFIDs (Radio Frequency IDentification), LEDs (Light EmittingDiode) or solar cells.

FIG. 2 is a flow diagram describing an example of the method for formingon a substrate an image or a pattern of a material. In a first step S100a layer of the desired material is provided on an intermediate carrier.It is then determined whether the material layer is provided in apattern or not, as is depicted in step S102. In case the material layeris provided in a pattern corresponding to the pattern to be transferredto the substrate, an adhesive or adhesion material layer is provided onthe patterned material layer in step S104. The adhesive material layermay be not patterned, i.e. may be applied over substantially the entiresurface of the intermediate carrier, or it may be patterned with apattern substantially corresponding to the pattern of the material layerso that the material to be applied to the substrate with the desiredpattern is covered substantially by the adhesive material layer. In casethe material layer is not patterned, in step S106 the adhesive materiallayer is provided with a pattern on the unpatterned material layer,wherein the pattern of the adhesive material layer corresponds to thepattern of the material to be applied to the substrate. In step S108 thematerial is transferred to the substrate with the adhesive materialfixing or “gluing” the material to a surface of the substrate.

In an example, the process may include a digital printing process, suchas inkjet printing, LEP printing, or dry EP printing without therequirement of providing any foils or a hot foiling process for fixingthe pattern or image between the substrate and the foil.

In an example, a blanket drum and an impression drums of an LEPapparatus are used in an alternate way, and an LEP ink is the adhesive(glue) material that may not just be applied via the photo imaging platedrum, but by any other digital method (e.g. inkjet printing on ablanket) or digital printing solution, which is able to print variableimages.

The material may be any material that cannot be reliably printed and/ortransferred onto the substrate and/or does not reliably adhere to thesubstrate after being applied thereto. Examples of such materials areconductive materials, like carbon nanotubes, metallic materials or, ingeneral, materials difficult to apply to the substrate using one of theabove described techniques.

The material layer may be provided on the intermediate carrier by one ofthe above mentioned techniques for obtaining the desired pattern in casea patterned material layer is to be provided. Alternatively, for examplewhen the material cannot be applied or is difficult to apply by one ofthe above mentioned techniques, an unpatterned layer of the material isapplied to the intermediate carrier and the desired pattern is generatedby applying the adhesive material with the desired pattern.

The approach is advantageous as it allows to apply substantially anymaterial to a substrate in a desired pattern without the need to modifyor optimize the material for a specific printing technique.Substantially no limitations with regard to the size, conductivity orthe like exist, rather, the material can be used as it is, therebyavoiding any changes in specific properties of the material afterapplying it to the substrate due to the conditioning thereof. It is nolonger needed to create a tacky adhesive film including the material orpayload, for example by providing metallic particles with a high pigmentloading for making the particles printable using inkjet technology,rather, the metallic particles can be used as they are without any needfor conditioning them for printing onto the substrate in the desiredpattern. When considering the LEP technology, for printing via theblanket roller in the LEP apparatus the payload material needs to betransferrable to the blanket, and then from the blanket to thesubstrate. Not all materials have this property, however, by applyingthe above approach any material can be printed and as an adhesivematerial layer an LEP ink, for example a transparent ink or pigmentedink or ink containing some functional material. The adhesive may be anykind of standard or non-standard ink including one created of functionalmaterial, may be used which is very adhesive and will glue the materialto the substrate.

FIG. 3 shows various examples for transferring a material with a desiredpattern to a substrate when applying a method as described above withregard to FIG. 2. FIG. 3(a) shows at a first position an intermediatecarrier 100 on one surface 102 of which a patterned material layer 104has been applied, for example by inkjet printing, EP printing, LEPprinting or any other suitable method. The material layer 104 ispatterned, as can be seen from FIG. 3(a), and the pattern corresponds tothe final pattern with which the material is to be applied to thesubstrate. Further, an adhesive material layer 106 is applied to thematerial layer 104. The adhesive material layer 106 is patterned withsubstantially the same pattern as the material layer 104, therebysubstantially covering the material 104. The adhesive material layer 106may be an LEP ink applied by an LEP process to the material layer 104.The intermediate carrier 100 as shown at the first position in FIG. 3(a)is then further processed as is shown at the second position in FIG.3(a). The intermediate carrier 100 having applied thereto the layers 104and 106 and a substrate 108 are brought together in such a way that theadhesive material layer 106 and a surface 110 of the substrate 108contact each other. The intermediate carrier 100 and the substrate 108may be brought together in such a way that a specific amount of pressureis applied. Due to the contact between the surface 110 of the substrate108 and the adhesive material layer 106, the adhesive material layer 106is fixed on the surface 110 of the substrate 108, wherein the strengthof the connection between the surface 100 and the adhesive materiallayer 106 is greater than the connection strength by which the materiallayer 104 is held on the surface 102 of the intermediate carrier. Duringthe further transfer process, the intermediate carrier 100 and thesubstrate 108 are separated from each other, as is shown at the thirdposition in FIG. 3(a) and due to the lower strength of the connectionbetween the material layer 104 and the surface 102 of the intermediatecarrier 100 when compared to the strength of the connection between theadhesive material layer 106 and the surface 110 of the substrate 108 thelayered structure comprising the material layer 104 and the adhesivematerial layer 106 is removed from the intermediate carrier 100 andremains on the surface 110 of the substrate 108. The substrate 108, nowincluding the desired pattern of the material 104, is shown in the lowerpart of FIG. 3(a). The material pattern 104 has been transferred to thesubstrate 108 and is fixed or “glued” to the surface 110 of thesubstrate 108 by means of the adhesive material 106.

FIG. 3(b) shows a similar process as in FIG. 3(a) and the same referencesigns are used. When compared to FIG. 3(a), in FIG. 3(b), as can be seenat the first position, the material layer 104 is not patterned, and itmay be applied to a part or to the entire surface of the intermediatecarrier 100. This process may be used when it is difficult to apply thematerial 104 by means of a printing approach as mentioned above. In thissituation, it is easier to simply apply the material 104 over thesurface of the carrier 100 and to define the pattern to be transferredby a patterned adhesive material layer 106 that may be applied by one ofthe above mentioned techniques. This allows precisely applying theadhesive material with the desired pattern, for example applying an LEPink in accordance with the LEP technology. As can be seen at the secondand third positions in FIG. 3(b), the transfer process results in atransfer of the patterned adhesive material layer to the surface 100 ofthe substrate 108 in a way as described above with regard to FIG. 3(a).Also a part 104 a of the material layer covered by the adhesive material106 is transferred, and some 104 b of the material remains on theintermediate carrier 100 after the transfer. Thereby the material istransferred with the desired pattern to the substrate, resulting, as isshown in the in the lower part of FIG. 3(b), in the same structure as inFIG. 3(a).

FIG. 3(c) shows yet another possibility for transferring a material withthe desired pattern to a substrate. When compared to FIG. 3(a), thedifference is that the adhesive material layer 106 is applied without apattern to substantially cover the entire surface of the intermediatecarrier 100, thereby covering the carrier's surface 102 and thepatterned adhesive material layer 104. This results in a substrate 100having the material 104 provided thereon in the desired pattern glued tothe surface by means of the adhesive material layer 106 now coveringsubstantially the entire surface of the substrate 100.

In FIGS. 2(a) to 2(c) the material layer 104 and the adhesive materiallayer 106 are provided on the same intermediate carrier 100. However, inaccordance with other examples, the material layer 104 may be providedon the intermediate carrier 100, and the adhesive material layer 106 maybe provided on a further intermediate carrier. This is described in FIG.3(d) on the basis of an example for obtaining a substrate with a definedpattern in a way as described with regard to FIG. 3(b). It is, however,noted that the approach described with regard to FIG. 3(d) may also beapplied to obtain the intermediate carriers shown at the first positionsin FIGS. 2(a) and (c). The intermediate carrier 100 has applied to itssurface 102 the non-patterned material layer 104. A further intermediatecarrier 112 is provided having applied to its surface 114 the patternedadhesive material layer 106. The intermediate carrier 100 and thefurther intermediate carrier 112 are brought together in a way as shownat the second position in FIG. 3(d) such that the adhesive materiallayer 106 contacts the material layer 104. The intermediate carriers100, 112 are then separated as shown at the third position of FIG. 3(d),thereby obtaining an intermediate layer 100 as the one depicted at thefirst position of FIG. 3(b), which is then further processed in a way asdescribed with regard to FIG. 3(b) for obtaining the substrate 108 withthe pattern of the desired material glued to its surface by means of theadhesive material.

FIG. 4 shows a schematic representation of an apparatus for forming on asubstrate a pattern of a desired material. The apparatus 200 includes aprint station 202 for printing an adhesive material layer onto amaterial layer. For example, as described above with regard to FIGS.2(a) and (b), the print station 202 may be part of an LEP apparatus forapplying a transparent LEP ink that fixes or “glues” the material to thesubstrate after its transfer so that the print station 202, as indicatedin FIG. 3, may be considered to apply a “digital glue image”. Theintermediate carrier 204 is provided with the material layer as isschematically represented by block 206 indicating that thenon-transferable image material is applied to the intermediate carrier204. The intermediate carrier 204, in an example, may be a blanket drumof an LEP apparatus and the block 206 may represent a station suitablefor applying either a layer of the material or a patterned layer of thematerial to the surface of the blanket drum 204. In a way as describedabove with regard to FIG. 3, by means of the print station 202 theadhesive material is applied to the material layer on the blanket drum204 and the thus generated two layered structure is forwarded towardsthe transfer station 208 formed by the blanket drum 204 and a pressuredrum 210 defining a nip 212 therebetween for receiving the media orsubstrate 214, for example a flexible material like paper. As thesubstrate 214 moves through the nip 212 the layered structure on thesurface of the blanket drum 204 is transferred onto the surface 216 ofthe substrate 214 in a way as described above with regard to FIG. 3.

The apparatus further comprises a control unit 218 controlling the printstation 202 and the operation of the other elements of the apparatus. Incase block 206 forms a further print station for applying the materialimage onto the blanket 204, the control unit 218 is also used forcontrolling this further print station 206, as is depicted by the dottedarrow line in FIG. 4.

The control unit 218 may cause the print mechanism 206 to print thematerial layer with a pattern in accordance with the pattern to beformed on the substrate 214 onto the drum 204, and may cause the printmechanism 202 to print the adhesive material layer with no pattern orwith a pattern corresponding to the patterned material layer onto thematerial layer. Alternatively, the control 218 may control the printmechanism 206 to apply the material layer without a pattern and maycontrol the print mechanism 202 to apply the adhesive material layer toa material in accordance with the pattern to be formed on the substrate214.

Thus, FIG. 4 shows an approach allowing to handle materials that aredifficult to print, e.g. using LEP technology. The material, by means ofthe print mechanism 206, is placed on the blanket drum 204, for exampleby analog or digital methods, such as inkjet printing, LEP printing, dryor liquid photographic printing or other suitable means. By means ofprint station 202 a digital or selective image is printed on top of thismaterial layer, for example by using transparent LEP ink, which adheresto the payload or material layer. The complete image is then transferredto the substrate 214, and the LEP ink, placed above the payloadmaterial, adheres to the media 214 creating a printed image with thepayload material on top.

In an example, on the hot blanket 204 the payload material may beprinted either selectively to form the image pattern (see FIG. 3(a)) oras a uniform film (see FIG. 3(b)). This is done without a transfer tothe substrate 214. A polymer material may be printed onto the payloadmaterial by the print station 202. The polymer material becomes a“glue”, for example when heated on the blanket drum 204. The polymermaterial may be applied either with the accurate form or patterncorresponding to the image to be printed or with a uniform film. Theblanket 204 is then engaged with the media 214 and the polymer filmadheres to the substrate or media 214 and to the payload materialcreating a glue between them, thereby generating the image on thesubstrate 214 with the payload material on top.

FIG. 5 shows a schematic representation of an LEP apparatus used forforming on a substrate a pattern of a specific material in a way asdescribed above with regard to FIG. 2. In FIG. 5, those elements alreadydescribed with regard to FIG. 4 have the same reference number and arepeated description thereof is omitted. In addition to the blanket drum204 a photo imaging plate PIP 220 is provided receiving the conductiveink at respective binary ink developers (BIDs) 220 a, 220 b arrangedalong the periphery of the PIP 220. The BID 220 a is provided forapplying a partially conductive ink onto the PIP 220 which can behandled by the LEP apparatus and can be transferred to the blanket 204,however, the ink is formed from a material which has no or reducedadherence properties on the substrate 214 and therefore it cannot beapplied by simply LEP printing it onto the substrate 214. Therefore, theapproach as described above with regard to FIGS. 1 and 2 is implementedin the LEP apparatus 200 of FIG. 5 in such a way that by means of asecond bit 202 b transparent ink or pigmented ink or ink containing somefunctional material forming the adhesive material layer, is provided.The adhesive may be any kind of standard or non-standard ink includingone created of functional material.

By means of the writing head 202/206, the charged PIP 220, which may benegatively charged, is discharged when, for example, a laser beam of thewriting head strikes the PIP. The ink is also charged, for examplenegatively, and is therefore attracted to the discharged portions orareas of the PIP 220. Any image generated by the inks on the PIP 20 istransferred via a further transfer station 222 between the PIP 220 andthe blanket drum 204 onto the blanket drum and from there in a way asdescribed above with regard to FIG. 4 to the substrate 214. Theapparatus 200 shown in FIG. 5 is operated under the control of thecontrol unit 218. During a first phase, the writing head 202/206 iscontrolled to apply an image onto the PIP 220 in accordance with thedesired pattern of the material layer. In this phase the BID 220 a isactive for applying the partially conductive ink to the discharged areasof the PIP 220 and for transferring them to the blanket 204 via thetransfer area 222. No substrate 214 is present in this phase at thetransfer station 208. During a second phase, the writing head 202/206generates a discharge pattern on the PIP 220 in accordance with thepattern with which the adhesive material layer is to be generated. Theadhesive material is provided by the transparent ink or pigmented ink orink containing some functional material via BID 220 b. In the secondphase, the transparent ink is transferred onto the material on theblanket 204, thereby generating an intermediate carrier in a way asdepicted in FIG. 3 and the layered structure on the blanket drum 204 istransferred onto the substrate 214 applied to the apparatus in thesecond phase, thereby generating on the substrate 214 the pattern of thematerial glued to the surface 216 by means of the transparent ink orpigmented ink or ink containing some functional material. The adhesivemay be any kind of standard or non-standard ink including one created offunctional material.

In the example of FIG. 5, the partially conductive ink may include thematerial to be printed onto the substrate 214, and the material may bein a phase in which it does not adhere to the substrate 214 but willadhere to the transparent ink. This may be done by significantlyreducing the content of resin, for instance the material may have 50% orless of the solids as resin, and the rest can be the material ofinterest. This allows the ink to be processed in accordance with the LEPprocess, however the amount of resin is sufficiently low for obtainingthe desired property or maintaining the desired property of the materialto be applied to the substrate. The modified material is applied to thesubstrate 204 by the above described approach using the melted layer ofresin formed by the LEP ink and arranged between the material ofinterest and the substrate.

For cleaning purposes a full page may be printed with the transparentink and transferred to a cheap media, thereby removing possiblebackground images from the respective intermediate carriers 204, 220.

In the example of FIG. 5, the LEP apparatus further includes a heater ordryer 223 for heating up the polymers to a temperature at which theybecome sticky so as to behave as a glue. Alternatively, the blanket drum204 may include an internal heater so that the blanket drum 204 isheated from inside.

FIG. 6 shows another example of an apparatus for forming on a substratea pattern of a desired material. In FIG. 6, the apparatus 200 receivesthe intermediate carrier 204 having provided thereon already theadhesive material layer 104 being patterned (as depicted in FIG. 6) orbeing non-patterned (as described above with regard to FIG. 3). In anexample, the apparatus 200 may include a print mechanism 206 operatingunder control of the control unit 218 for generating the material layer104 on the intermediate carrier 204. Alternatively, the intermediatelayer 204 having applied thereon the material layer 104 may be providedexternally and supplied to the apparatus 200. In such an example, noprint mechanism 206 is needed. The apparatus 200 comprises a furtherintermediate carrier 224 on which, by means of the print mechanism 202,the adhesive material layer (patterned as shown in FIG. 6 orunpatterned) is applied. The apparatus comprises a transfer station 226formed between the further intermediate carrier 224, which may forexample be a PIP similar to the one of FIG. 5, and a pressure drum 228.A nip 230 is defined between the drums 224 and 228 and the intermediatecarrier 204 having applied thereto the material layer 104 passes throughthe nip. When passing the nip 230, the adhesive material layer 106 istransferred from the drum 224 onto the material layer 104, therebyyielding the intermediate carrier 204 shown at the center of FIG. 6having applied thereto the layered structure including the materiallayer 104 and the adhesive material layer 106. The intermediate carrier204 is forwarded to a further transfer station 232 defining between twopressure drums 234 a and 234 b a nip 236. The nip receives theintermediate carrier 204 including the two layers 104 and 106 and thesubstrate 214, thereby bringing the substrate 214 and the intermediatecarrier 204 together such that the adhesive material layer 106 and thesurface 216 of the substrate 214 come into contact with each other sothat, as described above with regard to FIG. 3, the adhesive materiallayer 106 will be fixed to the surface 216 of the substrate 214 togetherwith the material 104 as is depicted at the right hand part of FIG. 6.The intermediate layer 204 may be discarded and may be recycled forfuture use for generating further patterns to be transferred.

FIG. 7 is a schematic representation of an example of an LEP printengine of FIG. 1 which has been modified for printing any type ofmaterial. For the sake of clarity the imaging part (charging, writingand cleaning) as described in FIG. 1 is not shown in FIG. 7. The BIDunits 16 a-16 c apply LEP ink 106 a-106 c which may comprise a simpleprocess color (CMYK), a transparent ink, a dielectric ink or functionalmaterials such as semiconductors. LEP-based inks 106 a-106 c may containenough resin so they can serve as glue or adhesive. The LEP material 106a-106 c is transferred to the ITM drum 18, where it is heated by anexternal heater 20 and/or an internal heater 20′ so that it dries andmelts. At the ITM drum 18, there are several applicators 24 a, 24 bwhich carry the functional materials 104 a, 104 b in a dispersed orviscous form on a roller, which is slightly touching the ITM drum 18.The functional material sticks 104 a, 104 b to the LEP material 106 andnot to the ITM drum 18 due to a blanket release layer 18 a.Alternatively the functional material 104 a, 104 b may be charged and anelectric field can repel it from the uncoated blanket drum 18. There areseveral applicators 24 a, 24 b of functional materials 104 a, 104 b,with only one of them being engaged with the ITM drum 18 at a time.Below the ITM drum 18 is the IMP drum 22, which can be dynamicallyengaged and disengaged with the ITM drum 18 using an engage mechanism(see the arrow 22 a).

In a first step, the IMP drum 22 is disengaged from the ITM drum 18, andthe ITM drum 18 continues to revolve and pick up additional layers ofLEP material 106. A layered structure 24 is shown as an example whichincludes a first layer of LEP material 106 ₁ on the ITM drum 18, asecond layer of the functional material 104 a on the first layer, and athird layer of LEP material 106 ₂ on the functional material 104. Thismay be repeated to create several layers of functional materials“sandwiched” between LEP materials (which can also be functional).

In the next step, the IMP drum 22 engages the ITM drum 18, and the“sandwich” 24 of one functional material is transferred to the IMP drum.The LEP material layer serves as glue, attaching the “sandwich” 24 to asubstrate 26 (such as paper or plastic). On the IMP drum 22, the ink 106may be re-heated by heaters 28 a, 28 b, to become sticky and to be ableto collect additional functional material 104 c on top. The additionalfunctional material 104 c may be provided by an applicator 30 whichcarries the functional material 104 c in a dispersed or viscous form ona roller, which is slightly touching the IMP drum 22.

In accordance with another example, a functional material applicator forapplication of the material both on the BKT (blanket) drum 18 and thesubstrate 26 provided on the IMP drum 22 may be used.

FIG. 8 shows an example of a multi-layer structure 24′ made by theprinting engine shown in FIG. 7. Functional materials 104 a, 104 b are“sandwiched” among LEP materials A, B and C. LEP Material A attaches thestructure 24′ to the substrate 26. Functional Material 104 c was addedin the final step on the IMP drum 22 by applicator 30.

FIG. 9 shows an example of a multi-layer functional device made by theprinting engine described with respect to FIG. 7. In this example thefunctional material layers are conductors and an LEP layer between themmay be dielectric, thereby forming a capacitor. In general the LEP layermay be semiconductive or resistive. FIG. 9(a) shows a cross-section ofthe layers, while FIG. 9(b) shows in 3D the pattered layers one abovethe other.

The steps to print the device shown in FIG. 9 are as follows: A firstlayer 106 a of LEP material is printed while the IMP drum 22 is engaged,and transferred to the substrate 26. The first layer 106 a is heated atthe IMP drum 22 and the functional material 104 c (a conductor in thisexample) is glued to the LEP Material 106 c. While the IMP drum 22 isstill engaged, an LEP dielectric material layer 106 b is transferredfrom the ITM drum 18 over the previous layers 106 a, 104 c on thesubstrate 26. The IMP drum 22 is disengaged, and the top LEP Material106 c is formed on the ITM drum 18, collecting onto it the functionalmaterial 104 b, which is also a conductor according to this example. TheIMP drum 22 engages again and both layers 104 b, 106 c are transferredto the substrate 26, finalizing the capacitor device. In this exampledevice the first and second conductive layers 104 b, 104 c, at the rightside in the Fig., overlay without any material there between so that thematerial will tend to attach each other to make a continuous conductingpath.

The pattern to be transferred to the substrate may be used in variousfields, for example for generating printed documents like greeting cardsor brochures. The process may also be used for generating electricalstructures, for example by applying carbon nanotubes on a substrate in adesired pattern. Different circuit patterns were obtained by usingcarbon nanotube ink in an apparatus as described above. The circuitpatterns include different conductive traces, for example conductorlines or spiral conductors that may be used in electrical circuits. Thecarbon nanotube ink used for generating the patterns have 40% of thesolid particles being the resin. This lack of resin results in a lackingor reduced adherence property of the image on the substrate so that thetransfer of the image from the blanket to the substrate become possibleby the above described approach, which resulted in an image with nobackground and a desired resistivity of several kΩ/□. FIG. 10 shows asample of carbon nanotubes printed on paper using the “gluing” concept.An ink including a high percentage (40% of the total solid materials) ofcarbon nanotubes (CNTs) was printed using the modified print engine ofFIG. 7. This ink was able to pass from the PIP drum 10 to the BKT drum18, creating on the BKT drum 18 an image. Thick CNTs layer are collectedon the BKT drum 18, by accumulating 16 layers of ink from the PIP drum10, with the IMP drum 22 disengaged. Due to the low content of resin theCNTs layer do not transfer and adhere to the substrate 26. The next stepis to print the required image pattern with yellow LEP ink. The IMP drum22 is engaged and the CNTs are transferred to the substrate 26 andadhere to it where the LEP ink is printed. The rest (background) imageremains on the BKT drum 18. A cleaner page is finally sent to clean thebackground image. From FIG. 10 it can be appreciated that the materialtransfer is very good and without any visible background image.

An example of forming on a substrate a pattern of a material provides apatterned adhesive layer on the intermediate carrier and subsequentlytransfers a material onto the adhesive layer, e.g. in case the materialis not controllable by printing methods, like a powder or a viscousmaterial which is not chargeable or jetable etc.

An example may alternatingly apply the adhesive and the material (e.g. adifferent material and/or a different adhesive during each stage) on anintermediate drum and finally transfer the stack onto the substrate.This allows creating a device with many layers. Alternatively, thelayers of adhesive and material may be applied layer after layer ontothe substrate. As a further alternative, a first part of the stack maybe created on the intermediate carrier and transferred to the substrateand then further layers may be applied to the stack on substrate.

An example may form a structure on the substrate where the adhesive ison the top, and then a material may be adhered onto the exposedadhesive.

The adhesive and the material may be applied with varying dimensionsand/or positions per element (e.g. for forming a device with a block inthe middle and a strip on the top and bottom).

Although some aspects have been described in the context of anapparatus, it is clear that these aspects also represent a descriptionof the corresponding method, where a block or device corresponds to amethod step or a feature of a method step. Analogously, aspectsdescribed in the context of a method step also represent a descriptionof a corresponding block or item or feature of a correspondingapparatus.

The above description is merely illustrative for the principles of themethod and apparatus for forming on a substrate a pattern of a material.It is understood that modifications and variations of the arrangementsand the details described herein will be apparent to others skilled inthe art. It is the intent, therefore, to be limited by the scope of theimpending patent claims and not by the specific details presented by wayof description and explanation herein.

The invention claimed is:
 1. A method for forming a multilayer device,the method comprising: providing a first patterned material layercomprising a pattern corresponding to a first, conductive pattern to beformed on a substrate, wherein material of the first patterned materiallayer comprises dry particles and wherein material of the firstpatterned material layer is applied as dry particles; providing acontinuous adhesive layer; transferring the material to the substratewith the adhesive fixing the material to a surface of the substrate,wherein the fixed material forms a conductive pattern; providing asecond patterned material layer comprising a second patterncorresponding to a second, semiconductor pattern to be transferred ontothe first patterned material layer; and transferring the secondpatterned material layer onto the first patterned material layer to forma multiple layer device wherein the adhesive fixes the second patternedmaterial layer to the first patterned material layer, wherein the secondpatterned material layer is a semiconductor.
 2. The method of one claim1, wherein providing the first patterned material layer comprisesprinting a functional material on an intermediate carrier.
 3. The methodof claim 2, wherein the first patterned material is printed by dry EPprinting and the second patterned material layer is printed by LEPprinting.
 4. The method of claim 1, wherein transferring the firstpatterned material layer to the substrate comprises bringing togetherthe intermediate carrier and the substrate such that the adhesive layeron the material layer comes into contact with a surface of thesubstrate.
 5. The method of claim 1, wherein the adhesive comprises apigmented ink.
 6. The method of claim 1, further comprising: printingthe adhesive layer onto the first material layer with a print station;and transferring the first material layer and adhesive layer to thesubstrate, the adhesive layer positioned to fix the material of thefirst material layer to the substrate.
 7. A method for forming a patternof a material on a substrate, the method comprising: providing acontinuous material layer of dry particles substantially free of polymerand polymer precursors; providing a patterned adhesive layer, a patternof the patterned adhesive layer corresponding to the pattern of materialto be formed on the substrate; consolidating the material layer usingheat and pressure; and transferring the material to the substrate withthe adhesive fixing the material to a surface of the substrate, whereinthe material layer comprises a pharmaceutical.
 8. The method of claim 1,wherein the first patterned material layer is substantially free ofpolymer and polymer precursor.
 9. The method of claim 1, wherein themultilayer device is a light emitting diode (LED).
 10. The method ofclaim 1, wherein the multilayer device is a radio frequencyidentification transponder.
 11. The method of claim 1, wherein themultilayer device is a solar cell.
 12. The method of claim 1, whereinthe multilayer device is a capacitor.